A very wide variety of bag and/or pouch constructions are well-known, for a variety of uses. The present invention particularly concerns bags or pouches used for the containment of articles or products. For example, a consumer product may be distributed and/or sold in a protective bag according to the present invention.
Such bags or pouches are conventionally sealed in a variety of manners, including with heat sealing, adhesives, mechanical fasteners and similar arrangements. Preferred embodiments of the present invention particularly concern pouches which are heat sealed, although other sealing methods may be used in embodiments involving the principles of the invention.
For many applications it is desirable to maintain an enclosed article substantially sterilized, prior to use. In some instances, items must be sterilized with heat, prior to being sealed within a pouch or the like. While this method of sterilization is effective for some uses, for many it is inappropriate. Reasons for this include: costs; potential damage to certain products or packages from sterilizing heat; and, inconvenience, especially with mass-manufacture processes.
It is also known that sterilization can be effected through the utilization of gas treatments such as with ethylene oxide. In a typical application, a pouch including a gas-permeable wall section is prepared, and the item to be sterilized is placed within the bag. The bag is then sealed. The sealed bag is placed in an ethylene oxide environment. The ethylene oxide can permeate the gas-permeable wall section, sterilizing the inside of the bag and products enclosed therein. If an appropriate gas-permeable material is selected, then bacteria cannot readily pass through the wall section, to re-contaminate the inside of the bag and/or products contained therein. That is, the gas-permeable material acts as a filter. As a result, the sealed product can be stored in a non-ethylene oxide environment, for a substantial period of time, without substantial contamination of the enclosed item.
A variety of pouch constructions have been developed which include gas-permeable wall sections therein, for gaseous sterilization. In some such systems, generally one end or edge of the bag comprises a "header" of the gas-permeable material. Such conventional arrangements have generally not been fully acceptable for numerous reasons. First, the arrangements using them have been relatively expensive to construct. Secondly, substantially complete equilibria within the bag, to obtain ethylene oxide penetration throughout substantially all portions of the bag and the enclosed items, has been slow to develop. Also, conventional pouch structures have not readily accommodated high-profile items, i.e. items which have a substantial thickness and require a bag to expand a considerable amount to be fit therearound.
A variety of materials can be utilized as the gas-permeable wall section. In general, what is required is a material: sufficiently strong and pliable for use as a portion of a pouch or the like; sufficiently permeable to gas; and, which acts as a filter to prevent passage of recontaminating bacteria or the like therethrough. Spunbonded high density polymeric (esp. polyethylene or polypropylene) materials, such as TYVEK (Dupont) are particularly well adapted for such uses.
Numerous other features are desirable in bag or pouch constructions, for certain applications. Some of these relate to, or concern, the following:
1. For some applications it is desirable that the pouch be expandable, to accommodate products of a variety of profiles. That is, it is desirable that the bag be such as can be easily expanded, and retained opened to receive an item or items therein. Some conventional arrangements, utilizing side gussets, have been developed to accommodate this. In general, these side gussets have been formed in bags of unitary structure, having a single seam therein. The seam, in general, has been placed along a side edge or back portion of the bag. The side gussets generally comprise an inward &gt; or &lt; shaped gusset in the sides of the pouch. Such gussets can act as a hinge, allowing front and back panels of the pouch to be collapsed toward or away from one another, in an accordion-like fashion. As a result of such arrangements, high-profile items can be easily stored within the bag.
2. In many instances, it is desirable that sealed bags, having products stored therein, include means facilitating easy opening. A variety of structures to accommodate these have been developed, including tear lines and notches.
As previously indicated, a very wide variety of bag or pouch designs have been developed. Many of these designs are well-suited for a variety of applications. However, improved designs have been needed to better accommodate: features for easy expandability to accommodate high-profile items stored therein; features facilitating easy opening; and, features facilitating utilization of a variety of materials, such as gas-permeable materials, for side panel members especially when such materials differ from the materials utilized for front and back panels in the pouch.